The 2013 WRX STI is available in both 4-door and 5-door mdoels, the WRX STI is powered by a 2.5-liter turbocharged/intercooled 4-cylinder BOXER engine, with Dual Active Valve Control System (Dual AVCS). The engine, which is exclusive to the STI model, produces 305 horsepower (SAE) at 6,000 rpm and 290 lb.-ft. of peak torque at 4,000 rpm. The 2013 WRX STI achieves the very stringent Bin 5 Tier 2-Federal (EPA) and LEV2-California Tier 2/Bin 5 emissions certification.
The WRX STI engine is based on a specially reinforced semi-closed deck engine block with high-strength cast pistons. A semi-closed deck design provides the same cooling efficiency as an open-deck cylinder block but with the higher strength of a full closed deck. Special reinforcing ribs in the block provide additional strength, and the crankshaft is nitride-hardened.
The turbocharger produces a maximum of 14.7 PSI of boost, compared to 14.2 PSI in the standard WRX. The WRX STI exhaust system features an efficient high-flow rear catalytic converter, low backpressure muffler and two sets of dual-outlet chrome tailpipes.
The WRX STI engine is teamed exclusively to a 6-speed manual transmission. Incline Start Assist can momentarily prevent the vehicle from rolling backward when being driven away from a stop on an incline.
Exclusive to the WRX STI, the Brembo® Performance Brake System uses ventilated 4-wheel Super Sport anti-lock (ABS) disc brakes with Electronic Brake-force Distribution (EBD). Front discs measure 13.0 inches in diameter and use 4-piston calipers; the 12.6 in. rear discs use 2-piston calipers. Taking input from a lateral g-sensor, a steering angle sensor, a yaw sensor and a brake pressure sensor, Super Sport ABS can control the braking forces at each rear wheel independently, which optimizes braking ability during hard cornering to help reduce understeer.
The WRX Limited 4-door includes standard 18 x 8.5 in. BBS® forged aluminum-alloy wheels. Dunlop SP600 245/40R18 summer performance tires are used with the standard and optional wheels.